Microwave Integrated Circuits (MICs) and Monolithic Microwave Integrated Circuits (MMICs) are the basis for low cost, high volume consumer electronics which operate below 3.0 GHz.
Filter components for these circuits are disproportionately large because the filter inductors necessary for their operation become exponentially larger with decreasing operating frequency. Large filter inductors severely reduce the cost advantages derived from using MICs and MMICs, however.
The need exists for compact, low cost filters to provide specific band-pass, low-pass, high-pass and band-stop frequency discrimination characteristics in radio frequency (RF) and microwave transmitters and receivers. In particular, when monolithic microwave integrated circuit (MMIC) circuits are selected to fulfill low cost, high manufacturing volume requirements, such filters must be integrated to maintain low cost. When conventional filters are translated into MMIC technology, however, they consume a disproportionate amount of substrate area, raising the cost per unit of high manufacturing volume circuits (especially when the operating frequencies are relatively low, e.g. less than 3.0 GHz).
It would be desirable to provide a method and apparatus to substantially reduce the area requirements for a typical filter on MMIC substrates, preferably by as much as a factor of five. It would be desirable if such a method and apparatus were applicable to MIC filters with similar size reduction results.